This invention relates to making and using certain alkoxysilane functional polymers, particularly those formed using seed oils and derivatives thereof and certain polyester polyols especially suitable for making the alkoxysilane functional polymers.
U.S. Pat. Nos. 3,627,722; 3,632,557; 3,979,344; 4,222,925; 4,374,237; 5,364,955 disclose variations on forming room temperature curable compositions by reacting isocyanate functionality in polyurethanes with silicon compounds. Generally the resulting silane capped polymers have alkoxysilane groups for curing with moisture. Bulky functional groups on the silanes were sometimes used to avoid excessive crosslinking. In some of the teachings, long polyurethane chains were used to avoid excessive crosslinking. Long chain polyurethanes can have undesirably high viscosity. Some such systems had low to negligible residual isocyanate functionality for the silanes to react with and were, therefore, impractical.
U.S. Pat. No. 5,990,257 taught silane capping of a polyurethane formed with a stoichiometric excess of polyol such that there were residual hydroxyl groups for reaction with a isocyanate functional silane. The resulting capped polymer was room temperature curable.
However, it would be desirable to avoid the use of a polyisocyanate and formation of a polyurethane, to produce a room temperature curable composition without formation of a polyurethane prepolymer and to avoid the excessive crosslinking that would be expected from reaction of a conventional polyether polyol with isocyanate-functional silane.
Moisture-cured isocyanate or silane functional polyols are known in the sealant market. These polyols are mostly based on polyethers (ethylene oxide/propylene oxide polymers) derived from petroleum feedstocks. The polyols are linear well-defined, high molecular weight intermediates, which have easy processability into standard sealant formulations. However, these sealants are hydrophilic and, as such demonstrate moisture uptake, mold growth and easy dirt pick up. In addition, the volatility of petroleum feedstock pricing and availability severely impacts the margins and pricing for these sealants. It would be advantageous to find new potential polyols from alternative feedstocks not tied to the petroleum industry, and extremely advantaged if such feedstocks were derived from renewable resources, such as natural seed oils. Desirably, such polyols could be formulated into analogous sealants in replacing polyether polyols using the same curing additive chemistry. Independently, the resultant sealants and coatings would have comparable mechanical properties, such as tensile strength and elongation as compared with commercial sealants formed using polyether polyols. Also independently, it would be desirable for the polyol, coating or sealant to be less hydrophilic and, thus, more resistant to moisture, mold and dirt pickup than are polyether polyol sealants and coatings.